1. Field of the Invention
This invention relates to electric cigar lighters, and more particularly to cigar lighters of the type which have automatic means for controlling the energizing current for the heating element.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97-1.99
The present invention more particularly concerns improvements in the cigar lighters that are illustrated and described in U.S. Pat. No. 4,544,226 dated Oct. 1, 1985 and entitled TWO-PIECE CLAMP SHELL FOR ELECTRIC CIGAR LIGHTER; U.S. Pat. No. 4,130,815 dated Dec. 19, 1978 and entitled FORMED HEATING RIBBON AND COIL; U.S. Pat. No. 3,909,587 dated Sep. 30, 1975 and entitled SPIRAL WOUND ELECTRICAL HEATING ELEMENT; U.S. Pat. No. 3,904,848 dated Sep. 9, 1975 and entitled CIGAR LIGHTER IGNITING UNIT; and in U.S. Pat. No. 3,532,849 dated Oct. 6, 1970 and entitled BIMETAL SHUNT FOR ELECTRIC CIGAR LIGHTER. The disclosures of these prior patents are included in the present application by way of reference.
The present invention also concerns improvements in the cigar lighters described and claimed in application U.S. Ser. No. 08/289,121 filed Aug. 11, 1994 and entitled ELECTRIC CIGAR LIGHTER HAVING COMBINED ASSEMBLER AND CONNECTOR PLUG AT ITS REAR, now U.S. Pat. No. 5,493,098 dated Feb. 20, 1996, which has common ownership with the above-identified patents. The disclosure of U.S. Pat. No. 5,493,098 is hereby incorporated, by reference, into the present application.
For many years automatic electric cigar lighters for automobiles have incorporated a bimetallic clip or latch in a panel-mounted receptacle or socket, such clip being adapted to latch onto a metal cup carried by a removable igniting unit. The metal cup contained a spiral-coiled heating element which, when energized to red heat, would heat and spread the bimetallic clip, releasing the igniting unit for removal from the socket. The heated element was then accessible and ready to be contacted by the tip of the cigar or cigarette to ignite the same.
Various safety measures were proposed to insure against malfunction and possible fire in such lighters. In U.S. Pat. No. 3,532,849 a second bimetallic member was for the first time introduced and arranged in the circuit so as to intentionally short-circuit the lighter and cause a line fuse at another location to blow out, usually such other location being a fuse block for the various car circuits.
U.S. Pat. No. 3,904,848 disclosed cost-cutting features in a cigar lighter, coupled with greater reliability of the igniting unit, to bring down the overall cost of the lighter and also to provide for a reliable replacement of the igniting unit.
In U.S. Pat. No. 3,909,587 improvements were made in the configuration of the heating element ribbon, to obtain a greater heat density and better stability and ruggedness, as well as reductions in cost.
U.S. Pat. No. 4,130,815 disclosed a different, unique heating coil configuration which made the coil more rugged and durable, as well as providing an improved heat density characteristic.
In U.S. Pat. No. 4,544,226 an improved sheet metal receptacle was proposed, which eliminated deep-draw operations and reduced the cost still further.
Still other improvements sought to attain better operation by modifications of the current control devices or bimetal switches that responded to the heat of the heating element, as well as better safety and maintenance of the lighter.
The various prior current-control devices mostly involved movable components such as bimetallic arms, clips, switch elements and the like, involving undesirable precise assembly operations and adjustments, circuit breaking arcs, radiation spikes and noises, and deterioration of contact surfaces, etc.